Process for the production of formaldehyde from methane



Dec. ,14; 1937. P. MASI-IAN VPROCESS FOR THE PRODUCTION OF FORMALDEHYDE FROM METHANE Filed MarchA 15, 1934 mm O.

INVE NTOR.

im M iw www M Y pf 10 reducing this portion of the gas.

Patented Dec. 14, 1937 UNITED STATES,

PATENT OFFICE.

raoosss- For. 'rnc PRODUCTION on Fo -I f mama Faoin ME'rnANE Paul Nashan, Oberhausen, Germany, assigner to the firm` Gutehoffnungshutte Oberhausen Aktiengesellschaft, Oberhausen Rheinland,

Application March 15, `In Germany 1934, semi No. 115,697

March 15, 1 933 1 claim. (ci. 26o-138) Processes have become known .yvltiich have the object of oxidizing methane into formaldehyde.

Also the attempt has been made to obtain an oxidation of the methane into formaldehyde from ja mixture consisting of one part by vlume ofmeth- 15 250 to fcentigrades together with methane and the nitric oxides carried with it, as it is passed over the nitric acid, these oxides taking part with a percentage by weight of'172. Besides the nitric oxides, no other catalysts are resorted to. But 20 none of these processes has been known `tohave resulted in a production of formaldehyde on com.-

mercial l-ines.v

The present process makes it possible to oxidize methane into l formaldehyde so as to obtain a '25 commercially satisfactory yield. This process consists inpassing through a catalyst chamber at a temperature of 600 to '150 centigrades and over` solid catalysts contained in said chamber the reaction mixture composed of methane or of a gas 30 containing methane and of a gas containing oxygen,fsuch asair for instance, together with a quantity of less Vthan one per cent of nitric oxides, calculated as NO, serving as Vgaseous catalysts. The hot solid catalysts consist of oxides of alka- 35 line earth elements included in the second group of the Periodic series, in admixture with a catalyst of the type which, if used alone, has the property of accelerating oxidation; viz., an oxide of aluminum, tungsten, manganese, nickel, chro'mi- 40 um, vanadium, molybdenum or cobalt. The materials may be used in the form of theirgxides or carbonates; the carbonates changing toA the oxides" when hot and in contact with air. Or, alloys of the metal or their mutualcompounds 4,5 may be used; these in turn being superflcially converted intdoxides by the hot gases. My mixture of, solid catalysts has the remarkable cxracteristic of stopping the oxidation'of methane at the,point desired; the production of vformalde-y 50 hyde. IThe nitric oxides act as oxidation catalysts to accelerate the action of `binding oxygen to methane.l The'oxidation, however, has a strong tendency to develop rather rapidly, beyond the voxidation stage for formaldehyde, intothat of o higher oxidation compounds, as CO-l-I-In and CO2 and COM-H2O, and this is the reason why oxidation' has to be stopped; all the more since the heat produced at every stage of oxidation raises the temperature existing in the reactionchamber in 60 aV short mbeyond the ignition point of the whole mixture which would cause complete com' bustion provided that a sufficient quantity of oxygen were present. In my p'rocess the only catalysts promotingl oxidation are the nitric oxides.

The solid catalyst mixture'is adapted to control,

oxidation; to prevent oxidation going on beyond the stage desired.

With the aid of the accompanying drawing illustrating diagrammatically byway of example an equipment suitable forcarryingout the process, the steps of the presentv process and the manner in which it is practiced, are set forth explicitly.

Element i represents a pump ori fan aspiring the methane or gases'containing methane, 2 is a pump or fan aspiring oxygen or gases containing oxygen, e. g. air. These two pumps deliver the two reaction bodies through the pipes d and 5 intoY the mixing receiver 3. The reaction mixture leaves the mimng receiver 3`through the pipe 6 to enter the catalyst chamber l, after it has taken up previously through the pipe 8' the nitric roxides,

which shall act as oxidation catalysts. As catalyst chamber 'l a multitubular vessel of heating 'tubes lhas been adopted which is heated at 9, or ywhich is entered by theheating gases at this point. The heating gases pass through the'intel rior of the tubes I@ and leave the vessel at Il!V through pipe l2. The remnant heat can be given oif in the mixer 3cr in any other apparatus. The space in the interior of the catalyst chamber entered by the reaction mixture holds the solid catalysts. The formaldehyde leaves the catalyst chamber together with the remnant gas at i3 and. passes through the piping lll and pipe coil l5l and through the cooler I6 into the receiver ll. Gut of this receiver the vapors and gases ow through the pipes' I8 into the scrubber I9. l'he products of condensation collected in the receiver ll run through the pipe '20 and those from the scrubber i9 through the pipe 2l into the receiver 22 where- 'fron the aqueous solution Ais returned by pump 23 through pipe 2l and through `the sprinkler 25 to the scrubber or is delivered by pump 26 into the concentrator 28. The' scrubber i9 is an apparatus wellknown in itselfequipped with baille plates or some other suitable'means, in which the aqueous solution of formaldehyde aspired by pumlp 26 and forced through the pipe 2l is coricentrated so as to obtain a marketable product. The portions which cannot be condensed in=the scrubber flow off through the discharge pipe 3l), 'while any undissolved gases collecting in the receiver 22 escape through the vent pipe 3l. The product obtained passes from 28 through pipe 29 and through the cooler 32 into the receiver 33. A As cooling agent for thecoolers I6 and 32 preferably water. is used whichenters at 34 and leaves at 35. 'The heating vapors ofthe concentrator 28 pass at 36 into thepipe coil, and are discharged at 31.

The gas mixture consisting of methane and oxygen or of the` gases containing these constituents and entering the catalyst chamber 'l will be heated, together with nitric oxides acting as gaseous catalysts, in this catalyst chamber to a temperature of 600-750 centigrades. The reaction components react with another under the action of the solid catalysts which stop oxidation at the formaldehyde stage and are further treated in the usual well-known manner as already set forth above, so as to make it possible to withdraw it from 33 as a marketable formaldehydefsolution. -1 Byfthe use of the solid catalysts in the catalyst chamber it has `been made possible to increase the yields obtained to the quantities stated in the following examples:

- Ei'ample 1 In the catalyst chamber 'l a mixture consisting of Mgo+25% sio2+15% zno was used as solid catalysts. Gas having apcrcentage of 'methane of 50 was used as reaction gas, while the oxidizing agent employed was air. As gaseous catalyst NO was made useof in a quantityamounting to 0.3% by volume, referred to the whole reaction mixture. At a working temperature of 720 centigrades a yield of 93 grams of HCHO was obtained per each -cubic metre of methane.

Example 2.

Catalyst: 95% Sion-4% CaO+1% vNaeCOs `lteaction gas: gas containing 50% CH4 r =v168 litres/h. Oxidizing agent: air =10001itres/h. Gaseous catalyst: NO -2.9 litres/h.;

x 0.25 by volume Working temperature: =715Vcentigrades Yield;` :112.0 grams of HcHo per cub, m. of GH,

Example 3 I catalyst: 40% ahoga-20% Mgo+5% Cao-q- 2% Fe2Os+20% SiOz+10% MoO3-|-3% Cr03 Reaction gas: gas containing 50% CH4" k =168 litres/h. Oxidizing agent: air =1000 litres/h. Gaseous catalystf NO l =2.9 litres/h y '0.25 by volume `Working temperature: =720 centigrades Yield; =9s.5 grams-r nono per cub. m. orcm Eaamplel catalyst: 52% Bao+12% caco3+ 5% coo+20% zro2|11% Mgcoa Reaction gas: gas containing 25% CH4 =500 litres/h. oxidizing agent: air =3000litres/h. Gaseous catalyst: N0 =4.51itres/h.=

0.15% by volume Working temperature: :725 centigrades Yield =186.0 grams of HCHO per cub. m. of CHa.

, Example 5 Catalyst: 25% Tioga-20% sro+5% Pbo+ Y 35% Zn0+12% NiOz-'l3% A103 Reaction gas: gas containing 50% CH;

=200 litres/h. Oxidizing agent: air =1400 litres/h. Gaseous catalyst; NO =6.4 1itres/h.=

l 0.4% by volume Working temperature: =675 centigrades Yield: grams of HCHO per cub. m. of CH4 Example 6 l Reaction gas: gas containing 50% CH4 =200 litres/h. Oxidizing agent: air =1600 litres/h. -Gaseous catalyst: NO -=8.1litres/h.=

. 0.45% by volume Working temperature: =680 centigrades Yfeid; =142.0 grams of HCHQ per cub. n1. or om l oxide in conjunction with a metal oxide catalyst which, when used alone, accelerates 'oxidation` of methane, said mixture serving to prevent substantial oxidation of the formaldehyde into undesirable products at the stated high 'tempera- \ture, and recovering` formaldehyde from the eiliuent gases.

lAUL NiAlSHlANI 

